Centrifuges



May 10, 1966 K. PAUSE 3,250,391

CENTRIFUGES Filed Sept. 9, 1964 2 Sheets-Sheet 1 May 10, 1966 K. PAUSE 3,250,391

CENTRIFUGES Filed Sept. 9, 1964 2 Sheets-Sheet 2 Inventor I LLFT P6745511 F401 (2 (4 J l M2522,-

fi M-w United States Patent 3,25%,391 CENTRIFUGES Kurt Pause, Zeder-nstrasse 13, Grevenbroich, Germany Filed Sept. 9, 1964, Ser. No. 395,233 Claims priority, application Germany, Sept. 10, 1963, P 32,558 4 Claims. (Cl. 210-369) The present invention relates to centrifuges.

More particularly, the present invention relates to that type of centrifuge which has a frustoconical drum pro vided at its smaller end with an end wall which is fixed to the shaft which rotates the drum. The inner side surface of the drum is formed with a sieve so that solids can be separated from liquids.

When a structure of this type is used in the sugar industry, for example, it is not possible for it to provide a white sugar which is ready to be marketed, because the action of the centrifugal force on the sugar crystals as they move along the separating sieve results in too much frictional rubbing of these crystals so that they do not have a proper outer appearance. Moreover, the sugar crystals leave the drum at such a high speed that they split when they strike against the wall of the centrifuge housing. Also, the output of such centrifuges is relatively small, because the extremely high centrifugal force required to separate the liquid sufficiently from the solid 7 particles necessitates a very small time during which it is possible for the material to remain at the relatively small area available for separation of the liquid from the solid particles, with the result that the material must be moved along the separating sieve in an extremely thin layer.

It is accordingly a primary object of the present invention to provide a centrifuge which will avoid the above drawbacks.

In particular, it is an object of the invention to provide a centrifuge which can eificiently separate liquid from a relatively thick layer of solid particles, so that the output of the centrifuge of the invention is greater than a conventional centrifuge.

Moreover, it is an object of the invention to provide a centrifuge which will automatically orient the solid particles in a manner enabling liquid to be efficiently sepa rated therefrom even though the layer of particles is relatively thick.

Furthermore, it is an object of the invention to provide a centrifuge capable of adjusting the thickness of the layer of solid particles in accordance with the characteristics thereof.

Also, it is an object of the present invention to pro vide a centrifuge which requires less centrifugal force than a conventional centrifuge so that damage to the solid particles by subjecting them to excessive friction or by hurling them with too great a force against a wall can be reliably avoided.

With these objects in view, the present invention includes, in a centrifuge, a rotary shaft and an outer centrifuge drum of substantially frustoconica-l configuration having opposed ends one of which is larger than the other and having an end wall closing the smaller end of the drum and centrally fixed to the shaft with the latter extending coaxially into the drum so that the latter rotates with the shaft. This end wall is formed within the drum with anannular chamber surrounding the shaft and communieating with the interior of the drum, and the drum has a frustoconical side wall joined to its end Wall, the drum being formed in its interior at the junction between the side and end walls thereof with an annular groove surrounding and spaced from the annular chamber. The end wall is formed with a plurality of cutouts uniformly distributed about the shaft and providing communication I 'ice between the annular chamber and groove, and in addition the end wall is formed with an additional plurality of cutouts uniformly distributed about the shaft and provid ing communication between the groove and the exterior of the drum. A sieve is carried by the drum in its interior in a position covering the annular chamber of the end wall. An inner solid drum coaxial-1y surrounds and is fixed to the shaft for rotation therewith, and this inner drum is surrounded by the outer drum and also has a fr-ustoconical configuration providing the inner drum with large and small open ends. The large open end of the inner drum is situated adjacent but spaced from the end wall of the outer drum to define therewith a gap forming a transition path for material flowing from the inner surface of the inner drum to the inner surface of the outer drum. Finally, there is situated in the region of the small end of the inner drum a means for throwing against the inner surface thereof material which is to be centrifuged. I

The novel features which are considered as character istic for the invention are set forthin particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 shows one possible embodiment of a centrifuge of the invention in a longitudinal sectional elevation; and

FIG. 2 is a fragmentary longitudinal sectional elevation of the outer centrifuge drum.

Referring now to the drawings, the centrifuge illustra ted therein includes an outer drum 1 of frustoconical configuration having opposed ends one of which is lager than the other, and the small end of the drum 1 is closed by an end wall 1a which is centrally fixed to the rotary centrifuge shaft 15 in any suitable way, this shaft being driven in the direction 11 by any suitable drive which does not form part of the invention and is not illustrated. The end wall 1a includes a portion 2 which may be integral with or fixed to the remainder of the end Wall 1a, and this portion 2 is formed with an annular chamber 16 surrounding the shaft 15 and communicating with the interior of the drum into which the shaft 15 extends; This portion 2 may itself be fixed directly to the shaft 15 so as to be joined in this way to the remainder of the end wall 1a. The junction between the frustoconical side wall and the, end wall of the drum 1 is formed in the interior of the drum with an annular groove which leaves between this groove and the chamber 16 a peripheral wall 4 of the end wall portion 2, and this peripheral wall 4 is formed with a plurality of cutouts or openings 3 uniformly distributed about the shaft 15 and providing communication between the chamber 16 and the groove which surrounds the end wall portion 2. A sieve 5 is fixedly carried by the inner surface of the end wall In to separate the chamber 16 from the interior of the drum 1, this chamber 16 being covered by the sieve 5.

At the elevation of the cutouts 3, the end wall 10 is formed with an additional plurality of cutouts 13 also uniformly distributed about the shaft 15 and these cutouts 13 provide communication between the groove and the exterior of the drum 1.

An inner solid drum 6 coaxially surrounds the shaft 15 and is surrounded by the outer drum 1. This inner drum 6 is also of a frustoconical configuration and has opposed open ends the larger of which is situated adjacent but spaced from the end wall 1a to define a gap 12 therewith. The diameter of the larger end of the inner drum 6 is such that this larger end is also located adjacent to the side wall of the outer drum 1. Thus, the larger end of the drum 6 is provided with an outwardly directed flange having a convexly curved annular surface directed toward the end wall 1a so that the width of the gap 12 gradually diminishes as its diameter increases up to the throat of the gap where the gap has its smallest width.

A means 9 is provided for throwing the work material against the inner surface of the drum 6, and this means 9 takes the form of a flat circular plate surrounding the shaft 15 and fixed at its inner periphery to a sleeve 9a through which the shaft 15 extends. This means 9, as well as the sleeve 9a, is constrained to rotate with the shaft 15 but is axially movable therealong. For this purpose a suitable key which is fixed to the shaft 15 can be slidably received in a longitudinal groove formed in the interior of the sleeve 9a, and the upper end of the groove by engaging the upper end of the key can limit the downward movement of the sleeve 9a so as to determine in this way the smallest possible width of the gap 12.

The inner surface of the drum 6 is fixed at the region I of the smaller end of the drum to a plurality of radial arms 17 which are also fixed to the means 9, 9a, so that in this way the drum 6 is constrained to rotate with the shaft 15 while being axially movable with the means 9.

FIG. 2 shows the side wall of the outer drum 1 through out its entire length. As is apparent from FIG. 2 the side Wall of the outer drum is formed with additional discharge openings 14 and 18.

The inner surface of the outer drum fixedly carries on inwardly directed projections of this inner surface a frustoconical sieve 8 which lines the inner surface of the outer drum and which is joined at its bottom periphery to the outer surface of the end wall portion 2, this bottom periphery' of the sieve 8 extending into the groove which is situated between the openings 3 and 13. A sieve or screen 7 of a much coarser mesh than the sieve 8 is situated between the latter and the inner surface of the outer drum.

The above-described structure operates in the following manner:

The materialwhich is to be centrifuged falls in the direction of the arrow F onto the circular plate 9 which throws the material in an umbrella-shaped path outwardly against the inner surface of the drum 6 while accelerating the material up to the speed of rotation of the centrifuge. The particles of sugar or the like which have the greater specific weight form under the action of the centrifugal force a layer engaging the inner surface of the drum 6, while the liquid which is of lesser specific weight engages the layer-of solid particles. As a result of the frustoconical configuration of the inner drum 6, both of these layers progress toward the end wall 1a. The liquid, however, flows toward the end wall 1a with a greater speed than the sugar and passes through the sieve into the chamber 16 from where it is thrown out of the centrifuge through the openings 3 and 13 and received ina known way to be collected and directed to a further station. The arrow 11 indicates the path of movement of the sugar layer Z, while the arrow indicates the path of movement of the liquid A.

In the region of the end wall 1a, the sugar layer Z, or the layer of other solid particles, is pressed into the gap 12 and reaches, in a layer of uniform thickness, the sieve 8, so that the gap 12 forms a transition path for the movement of the material from the inner surface of the inner drum to the inner surface of the outer drum. Inasmuch as the layer of particles of sugar or the like is necessarily situated against the inner surface of the drum 6 with the larger solid particles next to the inner surface of the drum 6 and the smaller particles more distant'from the inner surface of the drum 6, the layer of solid particles moving downwardly along the drum 6 will have the larger particles situated outwardly of the inner smaller particles. However, after moving through the transition gap 12, this situation of the particles in the layer is necessarily reversed inasmuch as the layer is in effect turned inside out as it traverses the gap 12 and advances upwardly along the sieve 8, so that at the inner surface of the outer drum the smaller particles are closer to the latter inner surface and are situated outwardly of the larger particles. As a result the liquid which still remains between the solid particles is quickly centrifuged outwardly through the sieves 8 and '7 to be discharged through the openings 13, 14 and 18. The layer of solid particles moves along the sieve 8 without any rearrangement of the particles and is discharged from the outer drum at its open larger end where the particles are received and conveyed away in a known manner. Of course, the liquid discharging through the openings 14 and 18 is also received and conveyed away in a known manner.

Thus, when the material is initially thrown against the inner surface of the inner drum 6, a sedimentation action takes place and in addition the larger crystals become located closer to the drum 6 outwardly of the finer crystals. Of course, the liquid at this time not only engages the layer of solid particles but is also situated in the spaces therebetween. The liquid layer will progress toward the bottom end wall of the centrifuge at a faster rate because of the lesser coefficient of friction of the liquid. The arrangement of the solid particles at the outer drum with the finer crystals outwardly of the larger crystals enhances the rapid centrifuging of the liquid out of the spaces between the solid particles.

Inasmuch as the largest particle liquid is eliminated before the layer reaches the outer drum, and inasmuch as the solid particles are situated very favorably at the outer drum for centrifuging of the liquid, it is possible to maintain the centrifugal force at such a low value that the solid particles will not split when they engage the wall of the housing of the centrifuge. Moreover, it is possible to provide drums of such a short length that the frictional rubbing of the sugar crystals is maintained at a degree which does not undesirably influence the crystals. Furthermore, because the layer is relatively thick the greatest part of the sugar crystals do not even engage the sieve 8. The output of the centrifuge of the invention is very high because of a relatively thick layer of sugar is constantly issuing from the outer drum.

When the structure is vertically arranged as shown in FIG. 1, the free vertical movability of the inner drum relative to the shaft 15 provides an automatic adjustment of the thickness of the layer of solid particles according to the properties thereof. However, it is possible to provide a structure enabling the adjustment of the gap 12 to be carried out manually or automatically. The convex curvature of the bottom surface of the flange at the bottom of the inner drum 6 greatly contributes to the uniformity of the charge which is delivered to the outer drum.

It will be understood that each of the elements described above, or two ormore together, may also find a useful application in other types of centrifuges differing from the types described above.

While the invention has been illustrated and described as embodied in rotary centrifuges, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a centrifuge, in combination, a rotary shaft; an outer centrifuge drum of substantially frustoconical configuration having opposed ends one of which is larger than the other and having an end wall closing the smaller end of said drum and centrally fixed to said shaft with the latter extending coaxially into said drum so that the latter rotates with said shaft, said end wall being formed Within said drum with an annular chamber surrounding said shaft and communicating with a space within said drum, and said drum having a frustoconical side Wall joined to said end wall, said drum being formed in its interior at the junction between said end and side walls thereof with an annular groove surrounding and spaced from said chamber, said end wall being formed with a plurality of cutouts uniformly distributed about said shaft and providing communication between said chamber and groove and with an additional plurality of cutouts uniformly distributed about said shaft and providing communication between said groove and the exterior of said drum; a sieve carried by said drum in the interior thereof and covering said chamber; an inner solid drum coaxially surrounding and fixed to said shaft for rotation therewith, said inner drum being surrounded by said outer drum and also having a frustoconical configuration providing said inner drum with large and small open ends, said large end of said inner drum being situated adjacent but spaced from said end wall of said outer drum and having an outer peripheral flange extending toward and terminating adjacent said side wall of said outer drum, said flange having an annular convexly curved outer surface directed toward said end wall of said outer drum to define therewith a gap which gradually diminishes in cross section as it increases in diameter, said gap being situated at least in part outwardly beyond said annular chamber and forming a transition path for material moving from the inner surface of said inner drum to the inner surface of said outer drum; and means situated inthe region of the small end of said inner drum for throwing against the inner surface thereof material which is to be centrifuged while accelerating the material.

2. In a centrifuge, in combination, a rotary shaft; an outer centrifuge drum of substantially frustoconical configuration having opposed ends one of which is larger than the other and having an end wall closing the smaller end of said drum and centrally fixed to said shaft with the latter extending coaxially into said drum so that the latter ro tates with said shaft, said end Wall being formed within said drum with an annular chamber surroundnig said shaft and communicating with a space within said drum, and said drum having a frustoconical side wall joined to said end wall, said drum being formed in its interior at the junction between said end and side walls thereof with an annular groove surrounding and spaced from said chamber, said end wall being formed with a plurailty of cutouts uniformly distributed about said shaft and providing comrnunication between said chamber and groove and with an additional plurality of cutouts uniformly distributed about said shaft and providing communication between said groove and the exterior of said drum; a sieve carried by said drum in the interior thereof and covering said chamber; an inner solid drum coaxially surrounding and fixed to said shaft for rotation therewith, said inner drum being surrounded by said outer drum and also having a frustoconical configuration providing said inner drum with large and small open ends, said large end of said inner drum being situated adjacent but spaced from said end wall of said outer drum to define therewith a gap forming a transition path for material moving from the inner surface of said inner drum to the inner surface of said outer drum; and means situated in the region of the small end of said inner drum for throwing against the inner surface thereof material which is to be centrifuged while accelerating the material.

3. In a centrifuge as recited in claim 2, said inner drum and said means being constrained to rotate with said shaft while being freely movable therealong so that the width of said gap can change.

4. In a centrifuge as recited in claim 3, means for adjusting the width of said gap.

No references cited.

REUBEN FRIEDMAN, Primary Examiner.

J. L. DE CESARE, Assistant Examiner. 

1. IN A CENTRIFUGE, IN COMBINATION, A ROTARY SHAFT; A OUTER CENTRIFUGE DRUM OF SUBSTANTIALLY FRUSTOCONICAL CONFIGURATION HAVING OPPOSED ENDS ONE OF WHICH IS LARGER THAN THE OTHER AND HAVING AN END WALL CLOSING THE SMALLER END OF SAID DRUM AND CENTRALLY FIXED TO SAID SHAFT WITH THE LATTER EXTENDING COAXIALLY INTO SAID DRUM SO THAT THE LATTER ROTATES WITH SAID SHAFT, SAID END WALL BEING FORMED WITHIN SAID DRUM WITH AN ANNULAR CHAMBER SURROUNDING SAID SHAFT AND COMMUNICATING WITH A SPACE WITHIN SAID DRUM, AND SAID DRUM HAVING A FRUSTOCONICAL SIDE WALL JOINED TO SAID END WALL, SAID DRUM BEING FORMED IN ITS INTERIOR AT THE JUNCTION BETWEEN SAID END AND SIDE WALLS THEREOF WITH AN ANNULAR GROOVE SURROUNDING AND SPACED FROM SAID CHAMBER, SAID END WALL BEING FORMED WITH A PLURALITY OF CUTOUTS UNIFORMLY DISTRIBUTED ABOUT SAID SHAFT AND PROVIDING COMMUNICATION BETWEEN SAID CHAMBER AND GROOVE AND WITH AN ADDITIONAL PLURALITY OF CUTOUTS UNIFORMLY DISTRIBUTED ABOUT SAID SHAFT AND PROVIDING COMMUNICATION BETWEEN SAID GROOVE AND THE EXTERIOR OF SAID DRUM; A SIEVE CARRIED BY SAID DRUM IN THE INTERIOR THEREOF AND COVERING SAID CHAMBER; AN INNER SOLID DRUM COAXIALLY SURROUNDING AND FIXED TO SAID SHAFT FOR ROTATION THEREWITH, SAID INNER DRUM BEING SURROUNDED BY SAID OUTER DRUM AND ALSO HAVING A FRUSTOCONICAL CONFIGURATION PROVIDING SAID INNER DRUM WITH LARGE AND SMALL OPEN ENDS, SAID LARGE END OF SAID INNER DRUM BEING SITUATED ADJACENT BUT SPACED FROM SAID END WALL OF SAID OUTER DRUM AND HAVING AN OUTER PERIPHERAL FLANGE EXTENDING TOWARD AND TERMINATING ADJACENT SAID SIDE WALL OF SAID OUTER DRUM, SAID FLANGE HAVING AN ANNULAR CONVEXLY CURVED OUTER SURFACE DIRECTED TOWARD SAID END WALL OF SAID OUTER DRUM TO DEFINE THEREWITH A GAP WHICH GRADUALLY DIMINISHES IN CROSS SECTION AS IT INCREASES IN DIAMETER, SAID GAP BEING SITUATED AT LEAST IN PART OUTWARDLY BEYOND SAID ANNULAR CHAMBER AND FORMING A TRANSITION PATH FOR MATERIAL MOVING FROM THE INNER SURFACE OF SAID INNER DRUM TO THE INNER SURFACE OF SAID OUTER DRUM; AND MEANS SITUATED IN THE REGION OF THE SMALL END OF SAID INNER DRUM FOR THROWING AGAINST THE INNER SURFACE THEREOF MATERIAL WHICH IS TO BE CENTRIFUGED WHILE ACCELERATING THE MATERIAL. 